Inhibition of marine biofouling by tannins

M.C. PÉREZ; M.T. GARCÍA; G. BLUSTEIN; M.E. STUPAK

Río de Janeiro, Brasil

Congreso; 13th International Congress on Marine Corrosion and Fouling; 2006

INHIBITION OF MARINE BIOFOULING BY NATURAL TANNINS M C Pérez*, M T García, G Blustein, M E Stupak CIDEPINT (Centro de Investigación y Desarrollo en Tecnología de Pinturas), La Plata, Argentina, * e-mail: biofouling@cidepint.gov.arbiofouling@cidepint.gov.ar Paints containing organotins were used to protect marine structures by reducing biofouling. However, increasing concerns about the negative effects of these compounds on marine non target organisms and environment have led to a ban on TBT-containing coatings. An alternative to toxic compounds is the use of natural products that are non-toxic but have antifouling properties. Tannins, natural water soluble complex polyphenolic substances, have high relative molecular weight (>500) and are common in most of the higher plant species. They precipitate proteins such as gelatin from solution (astringency), and are also important in industry, food and environmental sciences. In the last fifty years the anticorrosive properties of tannins were known. Subsequently a number of tannin-based products appeared on the market and found a certain amount of success as pre-treatment primers for use of rusted steel without requiring complete removal of the corrosion product. On the other hand, tannins show anticarcinogenetic and antimicrobial activities due to their antioxidative in protecting cellular components from oxidative damages, and due to they inhibit the growth of some kinds of fungi, yeasts, bacteria and viruses. The aim of this study is to test the effect of quebracho tannin as probable antifouling pigment in both laboratory and in the sea. Because of tannins have a high solubility in aqueous media and consequently they would leach rapidly, they were precipitated as aluminium tannate, which has an adequate solubility in sea water. In the lab, it was evaluated the effect of decreasing dilutions from a 1 g/L quebracho tannin solution and aluminium tannate saturated solution on Balanus amphitrite and Polydora ligni larvae. For field trials, plates of inert gels (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga amphitrite and Polydora ligni larvae. For field trials, plates of inert gels (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in inhibiting settlement (p< 0.05 by ANOVA test using STATISTICA program). A great decrease in microfouling diversity was observed, the green alga (PhytagelTM) containing aluminum tannate were exposed in Mar del Plata harbour, Argentine. Exposure of larvae to dilutions as low as 1:16 for quebracho tannin and 1:8 aluminum tannate saturated solution produced a loss of phototactic response and a reduction in appendage activity up to complete immobilization; as the concentrations were increased the effects were more evident. In all cases, when larvae were transferred to fresh artificial sea water they could retrieve their movements and follow their development. In field trials, after 28 days exposure in the sea, aluminium tannate was effective in